It is commonly known that there is increasing damage and loss caused by the rising deer population which, in search of food are migrating to populated areas. The result of this deer migration is an increase in property loss by damage caused to trees, plants and shrubs and other landscape materials surrounding homes and businesses. Thus, deer which are foraging for food wander onto private properties to eat landscaping material and such damage done by foraging deer to agriculture and forestry sections is extensive, according to reports issued by the U.S. Department of Interior Fish and Wildlife Services.
Many types of devices and methods have been and are presently being used to discourage animals, such as deer, from causing damage to landscaping material, such as perimeter fencing, which may or may not be electrified, as well as the covering of shrubs with some type of netting. These arrangements are time consuming and impair the aesthetics of the property to be protected. Furthermore, audio frequency emission systems for repelling deer presently in use are difficult to install and generally operate continuously thereby allowing deer to become accustomed to the constant audio output and thereby making the devices ineffective.
Moreover, there is a substantial hazard connected with vehicle collisions with deer due to deer crossing roads and highways, and escalating repair costs for vehicle damage as well as medical costs associated with such collisions are increasing all the time.
There is a need to provide a method or system for repelling deer that is convenient, is highly efficient and does not pose a physical risk to wildlife, pets and human beings. Prior art methods and systems for addressing these needs were either too expensive, inhumane, ineffective or a combination of all of these.
U.S. Pat. No. 5,278,537 to Carlo et al. discloses a device for generating only one frequency of electrical impulses at any one time. Although a square wave is initially generated by the device it is then converted into a sine wave with a single frequency. It also generates some frequencies in the audible range below 20 KHz which, of course, are annoying, and do not achieve our stated objective of preventing the deer from becoming accustomed to a single frequency.
U.S. Pat. No. 5,418,518 to Schenken et al. is a vehicle animal warning device in which one, or more audible tones can be produced while U.S. Pat. No. 4,566,085 to Weinberg relates to a high intensity ultrasonic generator for controlling pests and vermin by means of tone bursts which are varied to prevent the vermin or pests from becoming acclimated to the sound, however neither of these patents teach a square wave distortion in the audio output as well as frequency switching which are critical elements of the present invention.